Urinary incontinence affects millions of people, causing discomfort and embarrassment, sometimes to the point of social isolation. In the United States, it is estimated that 10-13 million patients seek medical care for incontinence each year.
Urge incontinence is a common type of urinary incontinence, in which a sudden, urgent need to pass urine causes involuntary urination before the patient can get to a toilet. Urge incontinence may be caused by damage to nerve pathways from the brain to the bladder or by psychosomatic factors, leading to involuntary bladder contraction. Urge and stress incontinence may also occur together, particularly in older women.
A large variety or products and treatment methods are available for personal and medical care of incontinence. Most patients suffering from mild to moderate incontinence use diapers or disposable absorbent pads. These products are not sufficiently absorbent to be effective in severe cases. They are uncomfortable to wear, and cause skin irritation, as well as unpleasant odors. Other non-surgical products for controlling incontinence include urethral inserts (or plugs), externally-worn adhesive patches, and drugs.
Exercise and behavior training are also effective in some cases in rehabilitating pelvic muscles and thus reducing or resolving incontinence. Patients are taught to perform Kegel exercises to strengthen their pelvic muscles, which may be combined with electrical stimulation of the pelvic floor. Electromyographic biofeedback may also be provided to give the patients an indication as to the effectiveness of their muscular exertions. But retraining muscles is not possible or fully effective for most patients, particularly when there may be neurological damage or when other pathologies may be involved.
Medtronic Neurological, of Columbia Heights, Minn., produces a device known as Interstim for treatment of urge incontinence. Interstim uses an implantable pulse generator, which is surgically implanted in the lower abdomen and wired to nerves near the sacrum (the bone at the base of the spine) in a major surgical procedure—sometimes six hours under general anesthesia. Electrical impulses are then transmitted continuously to a sacral nerve that controls urinary voiding. The continuous electrical stimulation of the nerve has been found to reduce or eliminate urge incontinence in some patients. The batteries in the pulse generator must be replaced every 5-10 years. The strength and frequency of nerve stimulation are programmable allowing the treatment to be tailored to the patient, and a hand-held programming device is available for this purpose.
U.S. Pat. No. 4,607,639, which is incorporated herein by reference, describes a method for controlling bladder function by nerve stimulation, typically of a sacral nerve. The anatomical location of at least one nerve controlling the muscles for the bladder and/or its sphincter is identified, and an electrode is placed on the nerve to selectively stimulate the nerve for continence and evacuation purposes. The electrode can be implanted in a patient either surgically or percutaneously and may be either removed after neurostimulation has achieved the desired result or may be left intact on the nerve for selective stimulation thereof. Further aspects and applications of these techniques are described in U.S. Pat. Nos. 4,739,764, 5,484,445 describes a system for anchoring a lead to the sacrum for purposes of long-term stimulation, typically for treatment of incontinence. Both of these patents are also incorporated herein by reference.
U.S. Pat. No. 3,628,538, which is incorporated herein by reference, describes apparatus for stimulating a muscle, using an electromyogram (EMG) signal sensed in the muscle. If the signal is greater than a threshold value, a stimulator circuit applies a voltage to electrodes adjacent to the muscle. The apparatus is said to be useful in overcoming incontinence.
Various types of electrodes have been proposed for applying electrical stimulation to pelvic muscles so as to prevent unwanted urine flow through the urethra. For example, U.S. Pat. No. 5,562,717 describes electrodes that are placed on the body surface, typically in the areas of the perineum and the sacrum, and are electrically actuated to control incontinence. U.S. Pat. No. 4,785,828 describes a vaginal plug having electrodes on an outer surface thereof. A pulse generator in the plug applies electrical pulses to the electrodes so as to constrict the pelvic muscles and prevent urine flow. U.S. Pat. No. 4,153,059 describes an intra-anal electrode, to which repetitive electrical pulses are applied in order to control urinary incontinence. U.S. Pat. No. 4,106,511 similarly describes an electrical stimulator in the form of a plug for insertion into the vagina or the anus. U.S. Pat. No. 3,866,613 describes a pessary ring having two electrodes thereon, which are energized to control incontinence. All of the above-mentioned patents are incorporated herein by reference.
U.S. Pat. No. 4,580,578, which is also incorporated herein by reference, describes a device for stimulating the sphincter muscles controlling the bladder. A supporting body is fitted into the patient's vulva between the labia, so that two electrodes attached to the supporting body contact the epidermal surface on either side of the external urethral orifice. Electrical impulses are applied to the electrodes to stimulate the region of the sphincter.
A book entitled Urinary Incontinence, edited by P. O'Donnell Mosby Publishers, 1997, which is incorporated herein by reference, describes clinical aspects relating to the diagnosis and a treatment of urinary incontinence.